I have a pair of these ST-6500s and they're not great. The earlier 8s STIs are far more robust; they pretty much always come good when you free up the pawls, but the 9s levers are not only harder to work on, they're also likely to fail in other ways eventually that don't seem to trouble the 8s STIs. There were even 7s versions of these first-generation levers.

If you go shopping for a pair, try to buy them of one of the guys who reconditions them and sells them with new hoods. Otherwise, try to find a pair with good hoods, because they're $40 NOS.

Looking closely at this pic, it seems as if the seller's given you 7 of 9 on maybe a 7s cassette body...

We need more pics of the hub. Figure out how to upload them here and get back to us.